It cracks me up that Mark, who is apprehensive to experiment on his own pennants, is right there with advice!
I will say, for the era Mark collects, I doubt he has many white pennants.
Rob - I am thrilled that you have jumped in with both feet. Sorry about the failures but I think the successes far outweigh them. Here's what you might use on the Namath pennant. The bleach is more of a gel.